1 files changed, 68 insertions, 0 deletions
diff --git a/js/src/tests/non262/expressions/short-circuit-compound-assignment-property-key-evaluation.js b/js/src/tests/non262/expressions/short-circuit-compound-assignment-property-key-evaluation.js
new file mode 100644
index 0000000000..2026aa25d1
--- /dev/null
+++ b/js/src/tests/non262/expressions/short-circuit-compound-assignment-property-key-evaluation.js
@@ -0,0 +1,68 @@
+// Test that property keys are only evaluated once.
+
+class PropertyKey {
+  constructor(key) {
+    this.key = key;
+    this.count = 0;
+  }
+
+  toString() {
+    this.count++;
+    return this.key;
+  }
+
+  valueOf() {
+    throw new Error("unexpected valueOf call");
+  }
+}
+
+// AndAssignExpr
+{
+  let obj = {p: true};
+  let pk = new PropertyKey("p");
+
+  obj[pk] &&= false;
+
+  assertEq(obj.p, false);
+  assertEq(pk.count, 1);
+
+  obj[pk] &&= true;
+
+  assertEq(obj.p, false);
+  assertEq(pk.count, 2);
+}
+
+// OrAssignExpr
+{
+  let obj = {p: false};
+  let pk = new PropertyKey("p");
+
+  obj[pk] ||= true;
+
+  assertEq(obj.p, true);
+  assertEq(pk.count, 1);
+
+  obj[pk] ||= false;
+
+  assertEq(obj.p, true);
+  assertEq(pk.count, 2);
+}
+
+// CoalesceAssignExpr
+{
+  let obj = {p: null};
+  let pk = new PropertyKey("p");
+
+  obj[pk] ??= true;
+
+  assertEq(obj.p, true);
+  assertEq(pk.count, 1);
+
+  obj[pk] ??= false;
+
+  assertEq(obj.p, true);
+  assertEq(pk.count, 2);
+}
+
+if (typeof reportCompare === "function")
+  reportCompare(0, 0);